Macular Vascularity in Ischemic Optic Neuropathy Compared to Glaucoma by Projection-Resolved Optical Coherence Tomography Angiography

Purpose: To compare macular vasculature in patients with primary open-angle glaucoma (POAG) and atrophic nonarteritic anterior ischemic optic neuropathy (NAION). Design: Prospective, cross-sectional study. Methods: Thirty-seven eyes with moderate and advanced POAG, 19 eyes with atrophic NAION, and 40 eyes of normal subjects were imaged using optical coherence tomography angiography (OCT-A). Macular ganglion cell complex (GCC) and peripapillary retinal nerve fiber layer (RNFL) thicknesses were measured in addition to macular superficial and deep vasculature after projection removal using custom software. Results: Linear models showed that while averaged peripapillary RNFL and macular GCC were not different between NAION and POAG eyes, both were significantly thinner than control eyes. Whole image macular superficial vessel density was significantly lower in NAION and glaucoma eyes (P = .003 and <.001, respectively) than in normal eyes, with lower vessel density in glaucoma than in NAION eyes (P = .01). Whole image and parafoveal deep macular vessels in glaucoma eyes (21.0%±8.7%, 24.4%±9.6%) were significantly lower than in control eyes (27.4%±8.6%, 31.9%±10.6%) (P = .01 and P = .01, respectively). No significant differences in deep vessels were observed between NAION and control eyes. Glaucomatous eyes had lower temporal and inferior parafoveal deep vasculature values than NAION eyes (P = .007 and .03, respectively). Conclusions: In NAION and POAG with similar RNFL and macular damage, macular OCT-A shows less involvement of superficial and deep vascular plexus in NAION in contrast to POAG, which might show a primary vascular insult in addition to secondary vascular damage due to ganglion cell damage.